1. Field of the Invention
The invention relates to a disk drive device containing a rotating data recording disk and a head suspension assembly.
2. Description of the Prior Art
In a hard disk drive device, at least one magnetic recording disk is mounted on a spindle motor, and a head suspension assembly is provided for each of the data recording surfaces of the magnetic recording disk. The head suspension assembly contains an arm member, a rear end of which is mounted on a shaft mounted on a frame of the hard disk drive device, a load beam, a rear end of which is fixed on a front end of the arm member, a flexure, a rear end of which is fixed on a front portion of the load beam, and a head/slider assembly fixed on the flexure. The magnetic recording disk is rotated by the spindle motor, and the head suspension assemblies are moved in a radial direction of the magnetic recording disk by a voice coil motor (VCM).
FIG. 1 shows a portion of the magnetic recording disk 1 and the head suspension assembly 2. The radial direction of the head suspension assembly 2 is shown by arrows 3A and 3B. The disk 1 rotates in a direction shown by an arrow R. A ramp element 4 is mounted outside the magnetic recording disk 1. The ramp element 4 contains a ramped surface 5 and a rest position 6 for each of the head suspension assembly 2. For the ramp element 4 shown in FIG. 1, two magnetic recording disks and four head suspension assemblies are used. However, only one magnetic recording disk 1 and only one head suspension assembly 2 are shown for simplifying the drawing.
When the head suspension assembly 2 is moved in the direction of the arrow 3B by the VCM after the completion of a read/write operation, a load/unload tab 8A provided on the front end of the head suspension assembly 2 rides on the ramped surface 5 and is stopped at the rest position 6. This scheme for accessing the head/slider assembly 10 shown in FIG. 2 to and from a data track of the surface of the disk 1, and for holding the head suspension assembly 2 at the rest position 6 of the ramp element 4 is called Load/Unload.
The ramp element 4 may be provided with a plate 7 extended therefrom and that plate resides beyond the outside perimeter of the disk 1. FIG. 2 shows a detail of the front portion of the load beam 8 of the head suspension assembly 2 and the ramp element 4. In FIG. 2, two head suspension assemblies 2 are shown. One end of a flexure 9 is fixed to the load beam 8, and a head/slider assembly 10 is fixed on the free end of the flexure 9. A MR (magnetoresistive) head 51 is mounted within a front portion of a slider, and these are called the head/slider assembly. When the head suspension assemblies are positioned at the load/unload rest position 6, the head/slider assemblies 10 are beyond the outside perimeter of the disk 1.
A bent portion 9A is provided on the flexure 9, and the bent portion 9A extending through an aperture 11 of the load beam 8 is positioned to face a surface 8B of the load beam 8. When a shock is applied to the hard disk drive device during the state when the load/unload tab 8A is positioned on the rest position 6 of the ramp element 4, head/slider assembly 10 tends to move in a direction of an arrow 12. In this motion process, the bent portion 9A engages with the load beam 8, to prevent the head/slider assembly 10 from having excess motion in the direction of the arrow 12 that would cause the head/slider assembly 10 to collide against the plate 7, or the opposing head/slider assembly 10 if the plate 7 is not present.
As the size of the hard disk drive device becomes small, a space or distance D.sub.1 between the surface of the head/slider assembly 10 and the plate 7 of the ramp element 4 is reduced to a small value, for example 0.2 mm. The inventors of the present invention have found that, in spite of the provision of the bent portion 9A, a front edge 10A or a rear edge 10B of the head/slider assembly 10 collides against the surface of the plate 7 of the ramp element 4 across the reduced distance D.sub.1 when an unexpected excess shock is applied to the hard disk drive device.
The collision is caused by a movement of the head/slider assembly 10 in a pitching direction shown by an arrow 13 around the bent portion 9A and the reduced space D.sub.1. The collision causes the following two problems. The first problem is that the ramp element 4 is made of an electrically nonconductive material, such as a plastic, and electrical charges accumulated on the ramp element 4 are transferred to the MR head 51 in the head/slider assembly 10 when it collides against the ramp element 4, so that the MR head 51 is damaged by the electrical charges. The second problem is that small pieces of plastic which are separated from the ramp element 4 due to the collision deposit on the surface of the head/slider assembly 10, and when the head/slider assembly 10 flies on the surface of the magnetic recording disk 1, the small pieces deposited on the head/slider assembly 10 contaminate or scratch portions of the surface of the disk 1. The damaged surface prevents the formation of an air bearing between the head/slider assembly 10 and the disk 1, so that the head/slider assembly 10 contacts on the damaged surface of the disk 1 during the read/write operation. The damage gradually spreads over the surface of the disk 1, whereby a desired read/write operation can not be performed on the damaged surface.
If the extended plate 7 is removed from the ramp element 4, the slider to slider separation distance D.sub.2 in the FIG. 2 for a small hard disk drive device can be small, 0.65 mm for example, that when a shock is applied to the hard disk drive device, the slider motions including the pitching in the direction 13 will cause the slider to slider contact thereby damaging the air bearing surface of the slider or the head.